Thin film magnetic head and method of manufacturing same

ABSTRACT

A thin-film magnetic head and a method of manufacturing the same in which a precise control of a pole width can be performed and a sufficient overwrite characteristic can be obtained. The thin-film magnetic head has a first insulating and second insulating layer, and first and second magnetic layers that include two magnetic poles are magnetically coupled. The first magnetic layer has a magnetic pole tip which has a uniform width portion, while a magnetic pole coupler is located in a back gap area in contact with the second magnetic layer and a yoke which magnetically couples the magnetic pole tip with the magnetic pole coupler. A recording-medium-side edge of the second insulating layer defines a reference position to an air-bearing surface, and a surface of the magnetic pole tip and edge surfaces of the third insulating layer are planarized in one plane.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a thin-film magnetic head havingat least an inductive-type magnetic transducer for writing and a methodof manufacturing the same.

[0003] 2. Description of the Related Art

[0004] Improvements in the performance of a thin-film magnetic head issought since a surface recording density of a hard disk device has beenimproved. A composite thin-film magnetic head having a structure inwhich, a recording head having a inductive-type magnetic transducer forwriting and a reproducing head having a magneto resistive (referred asMR) element for reading are stacked is broadly used as the thin-filmmagnetic head. The MR element includes an device using an effect ofanisotropic magneto resistive (referred as AMR) and another device usingan effect of giant magneto resistive (referred as GMR). The reproducinghead using the AMR element is called an AMR head or simply MR head, andthe reproducing head using the GMR element is called a GMR head. The AMRhead is used as a reproducing head whose surface recording density isover 1 gigabit per square inch, and the GMR head is used as thereproducing head whose surface recording density is over 3 gigabit persquare inch.

[0005] The AMR head has an AMR film having the AMR effect. The GMR headhas a structure identical to the AMR head except that a GMR film havingthe GMR effect is used instead of the AMR film. However, when the sameexternal magnetic field is applied, the GMR film exhibits greater changein resistance than the AMR film. As a result, the GMR head can increasethe reproduction output three to five times the AMR head.

[0006] A method in which the AMR film being used as the MR film isexchanged with a material with better magnetic resist reactive such asthe GMR film, and a method in which a pattern width of the MR film,especially the MR height is made appropriate are used as the methods ofimproving the performance of the reproducing head. The MR height is alength (height) from an edge of air bearing side to an edge of the otherside, and it is controlled by an etching amount of the air bearingsurface. The air bearing surface, here, is facing a magnetic recordingmedium and called a track surface as well.

[0007] On the other hand, performance improvements in a recording headhave been called while performances in a reproducing head has improved.A factor which determines the performance of the recording head is athroat height (TH). The throat height is a length (height) of a polebetween the air bearing surface and an edge of an insulator whichelectrically isolates a thin-film coil for generating magnetic flux. Areduction of the throat height is needed in order to improve therecording head performance. The throat height is controlled by anetching amount when the air bearing surface is processed.

[0008] To improve a recording density among the performance of therecording bead, a track density of magnetic recording medium is requiredto be increased. In order to achieve this, a recording head with anarrow track structure in which a width of the top and bottom pole onthe air bearing surface, which are formed on top and bottom sandwichinga write gap, is reduced from some microns to sub-microns. Semiconductorprocess techniques are employed to achieve the narrow track structure.

[0009] A method of manufacturing the composite thin-film magnetic headas an example of method of manufacturing the thin-film magnetic head ofthe related art will be described by referring to FIG. 39 through FIG.44.

[0010] As shown in FIG. 39, an insulating film 102 made of alumina(Al₂O₃), for example, of about 5 to 10 μm in thickness is deposited on asubstrate 101 made of aluminum oxide and titanium carbide (Al₂O₃—TiC),for example. A bottom shield layer 103 for a reproducing head is formedon the insulating film 102. A shield gap film 104 is formed on thebottom shield layer 103 by depositing alumina 100 to 200 nm in thicknessthrough sputtering. An MR film 105 of tens of nanometers in thicknessfor making up the MR element for reproduction is formed on the shieldgap film 104, and a desired shape is obtained by patterning throughphotolithography with high precision. Next, after forming a lead layer(not shown) on both sides of the MR film 105 as an extraction electrodelayer which is electrically connected to the MR film 105, a shield gapfilm 106 is formed on the lead layer, the shield gap film 104 and the MRfilm 105, and then the MR film 105 is buried in the shield gap film 104and 106. Further, a top shield serving as a bottom pole (referred asbottom pole in the following description) 107 made of magnetic materialssuch as permalloy (NiFe) used for both reproduction and recording headis formed on the shield gap layer 106.

[0011] As shown in FIG. 40, an insulating film such as a write gap layer108 made of alumina film is formed, for example, on the bottom pole 107,and a photoresist layer 109 in a desired pattern is formed on the writegap layer 108 through photolithography with high precision. Next, athin-film magnetic coil 110 as a first layer for an inductive recordinghead made of, for example, copper (Cu) is formed on the photoresistlayer 109 by, for example, plating method. A photoresist layer 111 in adesired pattern is formed covering the photoresist layer 109 and thecoil 110 through photolithography with high precision. Next, a heattreatment at 250° C., for example, is applied to have the coil 110flattened and have turns of the coil 110 insulated from each other.Further, a thin-film coil 112 as a second layer made of, for example,copper is formed by plating method. A photoresist layer 113 in a desiredpattern is formed on the photoresist film 111 and the coil 112 throughphotolithography with high precision, and a heat treatment at 250° C. isapplied to have the coil 112 flattened and have turns of the coil 112insulate from each other.

[0012] As shown in FIG. 41, an opening 108 a is formed by partiallyetching the write gap layer 108 in a position behind the coil 110 and112 (right-hand side in FIG. 41) in order to form a magnetic path.Further, a top yolk-cum-top pole (referred as a top pole in thefollowing description) 114 made of magnetic materials for recording headsuch as permalloy is selectively formed on the write gap layer 108, thephotoresist layers 109, 111 and 113. The top pole 114 has a contact withthe bottom pole 107 in the opening 108 a being magnetically coupled.Next, after the write gap layer 108 and the bottom pole 107 are etchedabout 0.5 μm by ion milling etching using the top pole 114 as a mask, anovercoat layer 115 made of such as alumina is formed. The thin-filmmagnetic head is completed after a track surface (air bearing surface)120 of the recording head and reproducing head are formed by applyingmachine grinding with a slider.

[0013]FIGS. 42, 43, and 44 illustrate a completed configuration of thethin-film magnetic head. Here, FIG. 42 shows a sectional view of thethin-film magnetic head orthogonal to the air bearing surface 120, andFIG. 43 is an enlarged cross-sectional view of parallel to the airbearing surface 120 and FIG. 44 is a plan view. FIGS. 39 to 42 show across section taken along the line A-A′ in FIG. 44. An illustration ofthe overcoat layer 115 is omitted in FIGS. 42 to 44.

[0014] It is important to form the throat height (TH), an apex angle(θ), a pole width (P2W) and a pole length P2L shown in FIGS. 42 and 43precisely in order to improve the performance of the thin-film magnetichead. The apex angle θ is an angle between the corner of the tracksurface of the photoresist layer 109, 111 and 113, and a straight lineconnecting the surface of the top pole 114. The pole width P2W providesa width of a recording track in a recording medium. The pole length P2Lrepresents the thickness of the pole. Further, in FIGS. 42 and 44, ‘TH0position’ represents a reference position 0 of the throat height, thatis, a position of a track-side edge of the photoresist layer 109 whichis an insulating layer, electrically isolating the thin-film coils 110and 112 from each other.

[0015] As shown in FIG. 43, a structure in which each sidewall of thetop pole 114, the write gap layer 108 and a portion of the bottom pole107 is vertically formed in a self-aligned manner is called a trimstructure. The trim structure prevents an increase of the effectivetrack width occurred through expansion of the magnetic flux generatedduring writing of a narrow track. As shown in FIG. 43, a lead layer 121as an extraction electrode layer being electrically connected to the MRfilm is provided on both sides of the MR film 105. However, anillustration of the lead layer 121 is omitted in FIGS. 39 to 42 and 44.

[0016]FIG. 45 illustrates a plan structure of the top pole 114. As shownin the illustration, the top pole 114 consists mostly of a yolk area 114a and a pole tip 114 b having almost a constant width W1 as the polewidth P2W. At a coupling point of the yolk 114 a and the pole tip 114 b,an outer frame of the yolk 114 has an angle α against a surface parallelto the air bearing surface 120, while an outer frame of the pole tip 114b has an angle β against the surface parallel to the air bearing surface120. Here, α is, for example, about 45 degrees and β is 90 degrees. Thewidth of pole tip 114 b defines the width of the recording track. Thepole tip 114 b includes an area F in front of the TH0 position (airbearing surface 120 side) and an area R behind the TH0 position (yolk114 a side). As shown in FIG. 4, the area F is constant on the flatsurface of the write gap layer 108, the area R and the yolk 114 a areconstant on an coil area (referred as apex in the following description)being swelled up, covered by the photoresist film 109, 111 and 113. 16.The publication relating to the shape of the top pole is, for example,Japanese Patent application Laid-open Hei 8-249614 (U.S. Pat. No.5,600,519).

[0017] Since the pole width P2W determines the track width of therecording head, the pole width P2W needs to be formed precisely.Especially, recently, to make high surface density recording possible,that is to form the recording head having a narrow track structure,micro lithography having a size of the pole width P2W of the top poleequal to or less than 1.0 μm is required.

[0018] As a method of forming the top pole, shown in, for example,Japanese Patent Application Laid-open Hei 7-262519 (U.S. Pat. No.5,438,747), frame plating method is used. In a case where the top pole114 is formed by frame plating method, a thin electrode film made of,for example, permalloy is formed all over the apex area by, for example,sputtering. Next, after applying a photoresist on it, a pattern isobtained through lithography procedure to form a frame (outer frame) forplating. The top pole 114 is formed by plating method having theelectrode film as a seed layer.

[0019] By the way, the apex area and the other areas have, for example,more than 7 to 10 μm difference in heights. A photoresist of 3 to 4 μmin thickness is applied on the apex area. If the photoresist with equalto or more than 3 μm in film thickness on the apex is needed, aphotoresist film with for example, equal to or more than 8 to 10 μm infilm thickness is formed in the lower part of the apex area since thephotoresist with liquidity gathers into a lower area.

[0020] To form a narrow track as described above, a frame pattern with awidth of about 1.0 μm depending on the photoresist film is needed to beformed. That is, micro pattern with a width of 1.0 μm or less has to beformed depending on the photoresist film with equal to or more than 8 to10 μm in thickness. However, forming the photoresist film with such athick film with a narrow pattern width has been difficult.

[0021] Further, during an exposure of photolithography, a light for theexposure reflects with the undercoat electrode film as a seed layer andthe photoresist is exposed by the reflecting light. As a result,deformation of the photoresist pattern occurs and so that a sharp andprecise photoresist pattern can not be obtained. Consequently, the toppole can not be formed in a desired shape since sidewalls of the toppole take a shape being rounded. Especially, as shown in FIG. 8, whenthe top pole width P2W is made further narrower to have W1′, the desiredwidth W1′ becomes harder to obtain. It is because the width of thephotoresist pattern defining the top pole width P2W is wider than thedesired value and the shape becomes the one shown with a dotted line inFIG. 8 since among the pole tip area 114 b, in an area R being placed onthe apex area, the reflecting light being reflected from the undercoatelectrode film includes not only the reflecting light of orthogonaldirection but the reflecting lights of diagonal direction or lateraldirection from the slope of the apex area resulting in giving aninfluence to photosensitivity of the photoresist layer. Among the poletip area 114 b, a width of the area F is an extremely important factorin defining the track width on the recording medium. As a result, if thewidth of the area F becomes wider than the value W1′ described above,the narrow track width as desired can not be obtained.

[0022] Same problems exists in the magnetic head claimed in the JapanesePatent Application Laid-open Hei 8-249614. It is because the width ofthe front area of the TH0 position cannot be controlled precisely underthe influence of an exposure of the photoresist layer given by thereflecting light from a slope of the apex area in diagonal and lateraldirection since the pole width from the TH0 position to the yolk areachanges moderately.

[0023] As shown in FIG. 46, the connecting area R from the TH0 to theyolk area 114 a of the pole tip area 114 b has about the same width withthe front area of the TH0 having a small cross sectional view area, themagnetic flux from the yolk area 114 a is saturated in the area R sothat the flux can not sufficiently reach the area F which determines thetrack width. For that, an overwrite characteristic, that is, acharacteristic in a case where a data is written on a recording mediumover the already-written data, becomes as low as 10 to 20 dB so that asufficient overwrite characteristic can not be obtained.

[0024] A publication relating to the present invention includes JapanesePatent Application Laid-open Hei 1-184611 and Japanese PatentApplication Hei 10-188225. An inductive thin-film magnetic head having amagnetic core which comprises a rectangular pole tip with about the samewidth with a track width facing a magnetic medium and a back core havinga wide cross sectional area of the pole tip, and an angle between thepole tip and the back core is about 90 degrees is claimed in theJapanese Patent Application Laid-open Hei 1-184611. In the JapanesePatent Application Laid-open Hei 10-188225, a inductive thin-filmmagnetic head is disclosed. In the magnetic head, a projected area whichdetermines the track width is formed on one side of the pole film, andthe size of each portion of the projected area is set to a specificvalue.

[0025] The present invention is designed to overcome the forgoingproblems. It is an object of the invention to provide a thin-filmmagnetic head in which precise control of the pole width is performedand, at the same time, a sufficient overwrite characteristic can beobtained even in a case where the pole width is reduced.

SUMMARY OF THE INVENTION

[0026] A thin-film magnetic head of the invention includes at least twomagnetic layers magnetically coupled to each other including twomagnetic poles in part of sides of the area facing a recording medium,the magnetic poles being opposed to each other with a gap layer inbetween; and a thin-film coil unit placed between the magnetic layerswith an insulating layer in between. At least one of the two magneticlayers including: a first magnetic layer portion with a constant widthfor defining a width of a recording track of a recording mediumextending from a recording medium opposite surface facing to therecording medium to an edge of the insulating layer closer to therecording medium or its vicinity; and a second magnetic layer portionmagnetically coupled to the first magnetic layer portion at the edge ofthe insulating layer or its vicinity. A step in the width direction isformed in a coupling point of the first magnetic layer portion and thesecond magnetic layer portion so as to have a width of the firstmagnetic layer portion at the coupling point smaller than a width of thesecond magnetic layer portion at the coupling point.

[0027] A method of manufacturing the thin-film magnetic head of theinvention includes a step of forming at least two magnetic layersmagnetically coupled to each other including two magnetic poles in partof sides of the area facing a recording medium, the magnetic poles beingopposed to each other with a gap layer in between; and a step of forminga thin-film coil unit between the magnetic layers with an insulatinglayers in between. At least one of the magnetic layers is formed so asto include a first magnetic layer portion with a constant width fordefining a width of a recording track of a recording medium extendingfrom a recording medium opposite surface facing to the recording mediumto an edge of the insulating layer closer to the recording medium or itsvicinity, and a second magnetic layer portion magnetically coupled tothe first magnetic layer portion at the edge of the insulating layer orits vicinity; and a step in the width direction is formed in a couplingpoint of the first magnetic layer portion and the second magnetic layerportion so as to have a width of the first magnetic layer portion at thecoupling point smaller than a width of the second magnetic layer portionat the coupling point.

[0028] In the thin-film magnetic head or the manufacturing method of thesame of the invention, the recording track width of the recording mediumis defined according to the specific width of the first magnetic layerportion. The first magnetic layer portion is magnetically coupled to thesecond magnetic layer portion whose width is wider than that of thefirst magnetic layer portion at the edge close to the recording mediumin the insulating layer or its vicinity, and a step in the direction ofthe width is formed at the coupling point.

[0029] Further, the step face of the second magnetic layer portion atthe coupling point may be substantially orthogonal to the extendingdirection of the first magnetic layer portion.

[0030] Further, the edges of the step face of the second magnetic layerportion may be rounded off.

[0031] Further, the width of the second magnetic layer portion may bealmost constant all through the area.

[0032] Further, the width of the second magnetic layer portion maydiffer depending upon the position.

[0033] Further, the width of the second magnetic layer portion maybecome wider as the distance from the coupling point becomes larger.

[0034] Further, in the thin-film magnetic head of the invention andmethod of manufacturing the same, one of the magnetic may include athird magnetic layer portion magnetically connected to the secondmagnetic layer portion having larger width and area than the secondmagnetic layer portion.

[0035] Further, in the thin-film magnetic head of the invention and themethod of manufacturing the same, the first magnetic layer portion andthe second magnetic layer portion may be formed in a same procedure in asame body.

[0036] Further, in the thin-film magnetic head of the invention and themethod of manufacturing the same, the first magnetic layer portion, thesecond magnetic layer portion and the third magnetic layer portion maybe formed in a same procedure in a same body.

[0037] Further, in the thin-film magnetic head in the invention and themethod of manufacturing the same, the first magnetic layer portion andthe second magnetic layer portion may be formed in a same procedure in asame body, and the third magnetic layer portion may be formed in adifferent procedure in a separate body from the first and secondmagnetic layer portion.

[0038] Further, in the thin-film magnetic head of the invention and themethod of manufacturing the same, the third magnetic layer portion maybe placed overlapping at least a portion of the second magnetic layerportion.

[0039] Further, in the thin-film magnetic head of the invention and themethod of manufacturing the same, the third magnetic layer portion maygo over the coupling point and be placed overlapping a portion of thefirst magnetic layer portion, and an edge of the third magnetic layercloser to the recording medium may be orthogonal to the extendingdirection of the first magnetic layer portion. In such a case, the widthof the first magnetic layer portion which determines the recording trackwidth of the recording medium is exactly constant all through the areafrom the orthogonally crossing point to the top area even if a concavecorner of the step face in the width direction at the coupling point isrounded off, since the coupling point of the first and the secondmagnetic layer portion is receded from the edge face of the thirdmagnetic layer. Here, the position of the edge surface of the thirdmagnetic layer portion may be set in the same position of the edge ofthe insulating layer closer to the recording medium. In such a case, thewidth of the first magnetic layer which determines the recording trackwidth of the recording medium is exactly the same all through the areaso-called a throat height.

[0040] Further, in the thin-film magnetic head of the current inventionand the method of manufacturing the same, at least some portion of thesecond magnetic layer portion may be set on the slope surface formed byan insulating layer. In such a case, even if a concave corner of thestep in the width direction at the coupling point is relatively quiterounded off due to the fact that the second magnetic layer portion isformed on the slope mentioned above, and so that a condition of exposureduring a procedure of a photolithography for forming the first magneticlayer portion is made worse, variance of the substantial width of thefirst magnetic layer can be avoided.

[0041] Another object, distinctive characters and effects of the currentinvention will be made clear in the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1A and FIG. 1B are cross sectional views for describing aprocedure of the method of manufacturing of a thin-film magnetic head ofa first embodiment of the current invention.

[0043]FIG. 2A and FIG. 2B are cross sectional views for describing theprocedure following FIG. 1A and FIG. 1B.

[0044]FIG. 3A and FIG. 3B are cross sectional views for describing theprocedure following FIG. 2A and FIG. 2B.

[0045]FIG. 4A and FIG. 4B are cross sectional views for describing theprocedure following FIG. 3A and FIG. 3B.

[0046]FIG. 5A and FIG. 5B are cross sectional views for describing theprocedure following FIG. 4A and FIG. 4B.

[0047]FIG. 6A and FIG. 6B are cross sectional views for describing theprocedure following FIG. 5A and FIG. 5B.

[0048]FIG. 7A and FIG. 7B are cross sectional views for describing theprocedure following FIG. 6A and 6B.

[0049]FIG. 8 is a plan view showing a plan structure of a completedthin-film magnetic head.

[0050]FIG. 9 is a plan view showing a plan structure of the top pole inthe thin-film magnetic head as shown in FIG. 8.

[0051]FIG. 10 is an enlarged plan view of a top pole for describing theoperation of the thin-film magnetic head shown in FIG. 8.

[0052]FIG. 11 is an enlarged plan view of the top pole for describing acomparative example of operation to the thin-film magnetic head shown inFIG. 8.

[0053]FIG. 12 is an illustration showing a over write characteristic ofthe thin-film magnetic head shown in FIG. 8 and the thin-film magnetichead of a related art.

[0054]FIG. 13 is a plan view showing a modification of the top pole ofthe thin-film magnetic head according to a first embodiment of theinvention.

[0055]FIG. 14 is a plan view showing another modification of the toppole of the thin-film magnetic head according to the first embodiment ofthe invention.

[0056]FIG. 15 is a plan view showing still another modification of thetop pole of the thin-film magnetic head according to the firstembodiment of the invention.

[0057]FIG. 16A and FIG. 16B are cross sectional views for describing aprocedure of the method of manufacturing of the thin-film magnetic headaccording to a second embodiment of the invention.

[0058]FIG. 17A and FIG. 17B are cross sectional views for describing theprocedure following FIG. 16A and 16B.

[0059]FIG. 18A and FIG. 18B are cross sectional views for describing theprocedure following FIG. 17A and 17B.

[0060]FIG. 19A and FIG. 19B are cross sectional views showing amodification of the thin-film magnetic head according to the secondembodiment of the invention.

[0061]FIG. 20 is a plan view showing a plan structure of the top poleand a top pole tip of the thin-film magnetic head according to thesecond embodiment of the invention.

[0062]FIG. 21 is a plan view plan view showing an enlarged planstructure of the top pole tip shown in FIG. 20.

[0063]FIG. 22 is a plan view showing a modification of a top pole tipshown in FIG. 21.

[0064]FIG. 23 is a plan view showing a modification of the top pole andthe top pole tip shown in FIG. 20.

[0065]FIG. 24 is plan view showing an enlarged plan structure of the toppole tip shown in FIG. 23.

[0066]FIG. 25 is a plan view showing another modification of the toppole and the top pole tip shown in FIG. 20.

[0067]FIG. 26 is a plan view showing modifications of the top pole andthe top pole tip of the thin-film magnetic head of the invention.

[0068]FIG. 27 is a plan view showing another modification of the toppole and the top pole tip of the thin-film magnetic head of theinvention.

[0069]FIG. 28 is a plan view showing a plan structure of the top poleand the top pole tip of the thin-film magnetic head according to a thirdembodiment.

[0070]FIG. 29 is a magnified plan view of a main portion of the top poleand the top pole tip shown in FIG. 28.

[0071]FIG. 30 is a plan view showing a modification of the top pole andthe top pole tip of the thin-film magnetic head according to the thirdembodiment.

[0072]FIG. 31 is a plan view showing another modification of the toppole and the top pole tip of the thin-film magnetic head according tothe third embodiment.

[0073]FIG. 32 is a plan view showing still another modification of thetop pole and the top pole tip of the thin-film magnetic head accordingto the third embodiment.

[0074]FIG. 33A and FIG. 33B are cross sectional views for describing aprocedure of the method of manufacturing of thin-film magnetic headaccording to a fourth embodiment.

[0075]FIG. 34A and FIG. 34B are cross sectional views following FIG. 33Aand FIG. 33B FIG. 35A and FIG. 35B are cross sectional views followingFIG. 34A and FIG. 34B.

[0076]FIG. 36A and FIG. 36B are cross sectional views for describing aprocedure of the method of manufacturing of the thin-film magnetic headaccording to a fifth embodiment.

[0077]FIG. 37A and FIG. 37B are cross sectional views following FIG. 36Aand FIG. 36B.

[0078]FIG. 38A and FIG. 38B are cross sectional views following FIG. 37Aand FIG. 37B.

[0079]FIG. 39 is a cross sectional view for describing a procedure of amethod of manufacturing thin-film magnetic head of a related art.

[0080]FIG. 40 is a cross sectional view for describing the procedurefollowing FIG. 39.

[0081]FIG. 41 is a cross sectional view for describing the procedurefollowing FIG. 40.

[0082]FIG. 42 is a cross sectional view illustrating the structure ofthe conventional thin-film magnetic head.

[0083]FIG. 43 is a cross sectional view showing a cross section parallelto an air bearing surface in the conventional thin-film magnetic head.

[0084]FIG. 44 is a plan view showing the structure of the conventionalthinfilm magnetic head.

[0085]FIG. 45 is a plan view showing a structure of a top pole in theconventional thin-film magnetic head.

[0086]FIG. 46 is a plan view of the top pole for describing problemsoccurred when applying micro lithography to the top pole in theconventional thin-film magnetic head.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0087] Preferred embodiments of the invention will now be described indetail with reference to the accompanying drawings.

[0088] [First Embodiment]

[0089] A method of manufacturing a composite thin-film magnetic head asa method of manufacturing a thin-film magnetic head according to a firstembodiment of the invention will be described with reference to FIGS. 1to 8. The thin-film magnetic head of the embodiment will be shownspecifically in the method of manufacturing the thin-film magnetic headof the embodiment and so that both will together be described in thefollowings. Each of FIGS. 1A to 7A shows a cross sectional view verticalto an air bearing surface and each FIGS. 1B to 7B shows a crosssectional view parallel to the air bearing surface of a top pole. FIG. 8illustrates a plan structure of the composite thin-film magnetic head.

[0090] In the manufacturing method according to the embodiment, as shownin FIG. 1A and FIG. 1B, an insulating layer 2 made of alumina (Al₂O₃),for example, of about 3 to 5 μm in thickness is deposited on a substrate1 made of aluminum oxide and titanium carbide (Al₂O₃ TiC), for example.Next, permalloy of about 3 μm in thickness is selectively formed on theinsulating layer 2 by plating with using a photoresist as a mask to forma bottom shield layer 3 for reproducing head.

[0091] Further, alumina of 100 to 200 nm in thickness, for example, isdeposited on the bottom shield layer 3 through sputtering to form ashield gap film 4. An MR film 5 of tens of nanometers or less inthickness is formed on the shield gap film 4 for making up an MR elementfor reproduction, and photolithography with high precision is applied tohave a desired shape. Next, after forming a lead layer (not shown) as anextraction electrode layer which is electrically connected to the MRfilm 5 on both sides of the MR film 5, a shield gap film 6 is formed onthe lead layer, the shield gap film 4 and the MR film 5, and the MR film5 is buried in the shield gap film 4 and 6.

[0092] Further, as shown in FIGS. 2A and 2B, a top shieldlayer-cum-bottom pole (called bottom pole in the following description)7 of about 3 to 4 μm in thickness made of, for example, permalloy isselectively formed on the shield gap film.

[0093] The bottom pole 7 corresponds to at least one of ‘two magneticlayers’ of the invention.

[0094] Next, after forming an inorganic insulating film such as asilicon dioxide film (SiO₂), for example, of about 1 to 2 μm inthickness on the bottom pole 7, an insulating film 8 for defining anapex angle and a throat height is formed by selectively patternedthrough taper etching. For the insulating layer 8, not only a silicondioxide but also an alumina film or a silicon nitride (SiN) film and soon may be used. Alternatively, the film may be formed by sputtering orCVD (Chemical Vapor Deposition) method. Next, a write gap layer 9 madeof an insulating film such as alumina film is formed on the bottom pole7 and the insulating layer 8.

[0095] As shown in FIGS. 3A and 3B, a first layer of a thin-film coil 10of 2 to 3 μm in thickness for an inductive recording head made of, forexample, copper (Cu) is formed on the write gap layer 9 by, for example,electroplating.

[0096] As shown in FIGS. 4A and 4B, a photoresist layer 11 is formed toa desired pattern through photolithography with high precision on thewrite gap layer 9 and the coil 10. Next, a heat treatment at 250° C. isapplied for flattening the coil 10 and insulating between the coils 10.

[0097] Further, a second layer of a thin-film coil 12 of 2 to 3 82 m inthickness made of, for example, copper is formed on the photoresistlayer 11 by, for example, electroplating. A photoresist layer 13 in adesired pattern is formed on the photoresist layer 11 and the thin-filmcoil 12 by lithography with high precision, and a heat treatment at 250°C. is applied for flattening the coil 12 and having turns of the coil 12insulated.

[0098] As shown in FIGS. 5A and 5B, an opening 9 a in the back (rightside in FIG. 5A) of the coil 10 and 12 is formed by selectively etchingthe write gap layer 9 to form a magnetic path. Next, an electrode film(not shown) which is to be a seed layer in electroplating is formed byforming NiFe-system alloy, which is a material with high saturation fluxdensity, of about 70 nm in thickness by, for example, sputtering beforeforming a top pole. A photoresist pattern (not shown) which is to be aframe for forming the top pole is formed by applying photoresist on theelectrode film, patterning it using photolithography and applying frameplating. After forming a top yolk-cum-top pole (called top pole in thefollowing) 17 of about 3to 5 in thickness by electroplating using thephotoresist pattern as a mask and the electrode layer as a seed layer,the photoresist pattern is removed. The top pole 17 takes a plan shapeas shown in FIG. 9, for example, and has a contact with the bottom pole7 in the opening 9 a and is magnetically connected. For the top pole 17,for example, a material with high saturation flux density such aspermalloy (NiFe) or ferrous nitride (Fen) may be used. The shape of thetop pole 17 will be described later. The top pole 17 corresponds to ‘atleast one of two magnetic layers’ in the invention.

[0099] As shown in FIG. 6A and FIG. 6B, a trim structure is formed byetching the write gap layer 9 and the bottom pole 7 about 0.5 μm by, forexample, ion milling using the top pole 17 as a mask.

[0100] As shown in FIGS. 7A and 7B, an overcoat layer 18 made of, forexample, alumina is formed covering all the surface. The thin-filmmagnetic head is completed by forming a air bearing surface (tracksurface) of the recording head and the reproducing head through a slidermachinning process.

[0101]FIG. 8 is a plan view of the thin-film magnetic head manufacturedthrough the method of manufacturing of the embodiment. In theillustration, the overcoat layer 18 is omitted. As shown, the throatheight (TH) is a length from the edge of the pole side of the insulatinglayer 8 (TH0) to an air bearing surface 20. Each of FIG. 1A to FIG. 7Acorresponds to a cross section taken along the line A-A′ in FIG. 8.

[0102]FIG. 9 illustrates a plan structure of the top pole 17. As shownin the illustration, the top pole 17 has a yolk area 17 a composing mostof the top pole having a width W3, a middle area 17 b having almost aconstant width W1 and a top area 17 c having almost a constant width W2narrower than W1. The center of each width direction of the yolk area 17a, the middle area 17 b and the top area 17 c are met with each other.The frame of the yolk area 17 a makes an angle α against a surfaceparallel to the air bearing surface 20, and the side frame surface ofthe middle area 17 b makes an angle β against a surface parallel to theair bearing surface 20 at the coupling point of the yolk area 17 a andthe middle area 17 b. The width of the middle area 17 b and the top area17 c each are almost constant all through the area. In the embodiment, αis about 45 degrees, for example, and β is about 90 degrees.

[0103] The position of the coupling point of the middle area 17 b andthe top area 17 c of the top pole 17 meets TH0 position or its vicinity.Here, ‘vicinity’ means a range of ±0.5 μm, for example, from TH0position. At the coupling point, the width of the middle area 17 b is W1and the width of the top area 17 c is W2 narrower than W1. That is, atTH0 position or its vicinity, there is a step in the width directionbetween the middle area 17 b and the top area 17 c. An end face (calledstep face in the following description) 21 of the middle area 17 b atthe step area makes an angle Υ against the side frame surface of themiddle area 17 b, makes an angle δ with the side frame direction (thatis a direction in which the top area 17 c is extending) of the top area17 c. In the embodiment, both the angle Υ and δ are about 90 degrees.That is, the step face 21 between the top area 17 c and the middle area17 b is substantially vertical to the side frame surface of the top area17 c. Here, ‘practically vertical’ means the angle δ between the mainportion of the top area 17 and the main portion of the step face 21 isabout 90 degrees including a case where the corner crossing the top area17 and the step face 21 is a sharp edge, and at the same time, where thecorner is rounded off. It is preferable to have the angle δ in a rangeof, for example, 75 to 120 degrees. A round shape of the cornermentioned above can be produced even a portion corresponding to thecorner of the mask for forming a photoresist pattern is a sharp edge.Further, even an angle of the portion facing the corner of the mask forforming the photoresist pattern is made exactly 90 degrees, when anamount of exposure is increased during the photolithography procedure,the angle δ of the top pole 17 formed through the procedure mentionedabove may be widened to 110 to 120 degrees. Here, the top area 17 c ofthe top pole 17 corresponds to ‘a first magnetic layer portion’ of theinvention, the middle area 17 b corresponds to ‘a second magnetic layerportion’ of the invention and the yolk area 17 a corresponds to ‘a thirdmagnetic layer portion’of the invention.

[0104] As shown in FIGS. 7A and 7B, the top area 17 c is placed on theflat write gap layer 9 and the middle area 17 b and the yolk area 17 aare placed on an apex area which is swelled like a hill made of thephotoresist layers 11, 13 and so on. The width W2 of the top area 17 ccorresponds to the top pole width PW2 defining the track width on therecording medium.

[0105] The following values are preferable, for example, as the size ofeach part shown in FIG. 9.

[0106] Length L1 of the yolk area 17=10 to 40 μm

[0107] Length L2 of the middle area 17 b=3.0 to 5.0 μm

[0108] Length L3 of the top area 17 c (=throat height TH)=0.5 to 1.0 μm

[0109] Width W1 of the middle area 17 b=2.0 to 4.0 μm

[0110] Width W2 of the top area 17 c=0.6 to 1.2 μm

[0111] Width W3 of the yolk area 17 a=20 to 40 μm

[0112] The thin-film magnetic head with the top pole 17 having such ashape exhibits a high performance in overwrite characteristic. That is,in the top pole 17 as shown in FIG. 17, the width of the middle area 17b coupled to the top area 17 c at TH0 position is W1 much larger thanthe width W2 of the top area 17 c which defines the track width on therecording medium, and a volume (or a magnetic volume) of the middle area17 b is much larger than a portion R of the related art (FIG. 46). Forthis reason, a magnetic flux occurred in the yolk area 17 a by thethin-film coil 10 and 12 are not saturated in the middle area 17 b andreaches the top area 17 c with sufficient amount. Accordingly, even ifthe top area 17 c is applied to a narrow track width such as sub-micron,a sufficient amount of a magnetic flux for overwrite can be obtained.That is, a sufficient overwrite characteristic can be obtained whilenarrow track is being obtained.

[0113]FIG. 12 shows the overwrite characteristic of the thin-filmmagnetic head of both the related art and the embodiment comparing witheach other. (A) of FIG. 12 shows the overwrite characteristic of theconventional thin-film magnetic head having a top pole 114 shaped shownin FIG. 45, and (B) of FIG. 12 shows the overwrite characteristic of thethin-film magnetic head of the embodiment having the top pole 17 shapedas shown in FIG. 9. As shown in the figure, the overwrite characteristichas been improved as the value of the thin-film magnetic head of therelated art is 26.0 dB, while the value of the thin-film magnetic headof the embodiment is as high as 35.5 dB.

[0114] Further, the thin-film magnetic head with the top pole 17 havinga shape described above has advantages as follows even in themanufacturing procedure. That is, as shown in FIG. 10, in the top pole17 of the thin-film magnetic head of the embodiment, the angle δ betweenthe step face 21 at the coupling point of the top area 17 c and themiddle area 17 b and the side frame surface of the top area 17 c isabout 90 degrees. As a result, the reflection from the apex area inslanting and side direction occurred during a procedure ofphotolithography when selectively patterning a photoresist by exposureusing a mask is almost shut at the corner of 90 degrees between the stepface 21 at TH0 position or its vicinity and the side frame face of thetop area 17 c. Therefore, the reflection is effectively from reaching aphotoresist region for forming the top area 17 c. Accordingly, wideningof the pattern width of the photoresist region for forming the top area17 c can be suppressed. To be specific, as shown in FIG. 10, a length d1of part (dotted line in the figure) made wider than a desired width inthe top area 17 c in the longitudinal direction of the top area 17 c canme made extremely short.

[0115] On the other hand, as shown in FIG. 11, in a case where the angleδ between the step face 21 at TH0 position and the frame side surface ofthe top area 17 c is much larger than 90 degrees (for example, 130degrees), the above mentioned shutting effect of the reflection in thecorner is small so that the length d2 of part (dotted line in thefigure) made wider than the desired width W2 in the top area 17 cbecomes longer.

[0116] As described above, the width of the top area 17 c defining thewriting track width on the recording medium can be set to a target valueW2 so as to make it possible to have the writing track width narrowsince widening of the pattern width of the photoresist region forforming the top area 17 c of the top pole 17 can be prevented with thethin-film magnetic head of the embodiment.

[0117] As described, with the thin-film magnetic head of the embodiment,a step in the width direction which substantially changes to aright-angle is provided between the top area 17 c and the middle area 17b of the top pole 17 at TH0 position or its vicinity, and the width ofthe middle area 17 b is made sufficiently wider than that of the toparea 17 c which defines the track width, so that widening of the patternwidth of the photoresist for forming the top area 17 c can be preventedto have the writing track width micronized, and the flux occurred in theyolk area 17 a is suppressed to be saturated before reaching the toparea 17 c so as to maintain a sufficient overwrite characteristic.

[0118] Further, the insulating layer 8 defining the throat height TH isformed with inorganic insulating film in the embodiment, so that a shiftof the edge of the insulating layer 8 (or pattern shift) and profiledeterioration do not occur through a heat treatment at about 250° C. toform the coils 10 and 12. As a result, the throat height can becontrolled precisely. Further, the MR height and the apex angle θ can bealso controlled precisely.

[0119] Further, in the embodiment, the insulating layer 8 for definingthe throat height is formed with an inorganic film so that a patternshift of the insulating layer 8 does not occur while etching the writegap layer 9 and the bottom pole 7 to form a trim structure which alsoresults in obtaining a precise control of the throat height.

[0120] Further, in the embodiment, a thick insulating layer 8, besidesthe thin write gap layer 9, is formed between the bottom pole (topshield) 7 and the thin-film coils 10 and 12 so that a large dielectricwithstand voltage between the bottom pole (top shield) 7 and thethin-film coils 10 and 12 can be obtained, and at the same time, a fluxleakage from the thin-film coils 10 and 12 can be decreased.

[0121] In the embodiment, NiFe or ferrous nitride (FeN), for example,are used as the top pole 17, however, materials with high saturationflux density such as amorphous of Fe-Co-Zr, for example, can be used ormore than two kinds of these materials stacked together can be used aswell. Further, a magnetic material made up of NiFe and the materialswith high saturation flux density mentioned above being stacked togethercan be used as the bottom pole 7.

[0122] Further, the top pole 17 is not limited to the shape shown inFIG. 9. Shapes shown in FIGS. 13 to 15 may also be applicable.

[0123]FIG. 13 is a plan view of the top pole 17 of which both outercorner of the step face 21 of the middle area 17 b at TH0 position isslightly rounded off. The structure except for the part rounded off isidentical to FIG. 9. In such a case, the width of the step face 21 afterbeing rounded off is made same with W1.

[0124]FIG. 14 is a plan view of the top pole 17 of which an angle δbetween the step face 21 and the side frame surface of the top area 17 cat TH0 position is made larger than 90 degrees. The angle δ is made, forexample, 90 to 150 degrees, however, a range of 90 to 120 degrees ismore preferable.

[0125]FIG. 15 is a plan view of the top pole 17 of which the angle τbetween the side frame surface of the middle area 17 b and a surfaceparallel to the air bearing surface 20 is made smaller than 90 degrees.However, the angle τ is more preferable to be set in a range from 70 to80 degrees.

[0126] In FIGS. 13 to 15, the coupling point of the top area 17 c andthe middle area 17 b is not necessarily met exactly with TH0 positionbut may be shifted within a range of about, for example, ±0.5 μm fromTH0 position.

[0127] With the thin-film magnetic head having a top pole 17 shown inFIGS. 13 to 15, same effect as the thin-film magnetic head having a toppole 17 shown in FIG. 9 can be obtained.

[0128] [Second Embodiment]

[0129] Next, a second embodiment of the invention will be described.

[0130] A method of manufacturing of a composite thin-film magnetic headas a method of manufacturing the thin-film magnetic head of the secondembodiment will be described with reference to FIGS. 16A and 16B toFIGS. 19A and 19B. The thin-film magnetic head of the embodiment will beshown specifically in the method of manufacturing of the thin-filmmagnetic head of the embodiment and so that both will together bedescribed in the followings. Each of FIG. 16A to FIG. 19A illustrates across sectional view orthogonal to the air bearing surface and each ofFIG. 16B to FIG. 19B illustrates a cross sectional view parallel to theair bearing surface of the top pole area. In the figures, like numeralsare adopted to the same elements as those in the above mentionedembodiment.

[0131] In the method of manufacturing the thin-film magnetic headaccording to the embodiment, the procedure of forming from theinsulating layer 2 to the bottom pole 7 shown in FIG. 16A and FIG. 16Bwill be omitted since it is identical to that of the first embodimentshown in FIG. 3A and FIG. 3B.

[0132] In the embodiment, after the bottom pole 7 as shown in FIGS. 16Aand 16B is formed, the write gap layer 9 as shown in FIG. 17A and FIG.17B is formed and an insulating pattern 25 for defining the throatheight TH is formed on the write gap layer 9. Next, an opening 9 a forforming a magnetic path is formed by selectively etching the write gaplayer 9 in a position which is back (right-hand side in FIG. 17A) of theregion where a thin-film coil 29 is formed in the later procedure. Next,a top pole tip 27 a which is to be a portion of the top pole is formedselectively in a area form the insulating pattern 25 to the area of thetrack-opposite-surface side (air bearing surface side) by, for example,electroplating and, at the same time, a magnetic path forming pattern 27b is formed in the opening 9 a. For example, materials with highsaturation flux density such as alloy including permalloy (NiFe) oralloy including ferrous nitride (FeN) are used as the top pole 27 a andthe magnetic path forming pattern 27 b.

[0133] The top pole tip 27 a and the magnetic path forming pattern 27 bare formed as follows, for example. First, an electrode film (not shown)as a seed layer for electroplating is formed by about 70 nm in thicknessthrough, for example, sputtering. The seed layer is made of alloyincluding NiFe which is a material with high saturation flux density.Next, a photoresist pattern (not shown) is formed by applyingphotoresist on the electrode film, patterning it by photolithography andapplying frame plating. Next, the top pole tip 27 a and the magneticpath forming pattern 27 b of about 3 to 5 μm in thickness are formed byelectroplating using photoresist pattern as a mask, and the electrodefilm as a seed layer, then, the photoresist pattern is removed. The toppole tip 27 a takes a shape shown in FIGS. 20 and 21, for example. Theshape of the top pole tip 27 a will be described in the followings.

[0134] Next, a trim structure is formed by etching the write gap layer 9and the bottom pole about 0.3 to 0.5 μm by, for example, ion millingusing the top pole 17 as a mask. The trim structure is for suppressingthe widening of the substancial track width when writing.

[0135] Next, after forming an insulating film 28 of 0.5 to 1.5 μm inthickness, made of such as alumina film all over, a thin-film coil 29 of2 to 3 μm in thickness made of, for example, copper (Cu) for aninductive recording head is formed by, for example, electroplating.After forming an insulating film 30 of about 3 to 4 μm in thickness madeof such as alumina film all over, the top surfaces of the top pole tip27 a and the magnetic path forming pattern 27 b are exposed by polishingso that the whole surface is flattened through, for example, CMP(chemical machine polishing).

[0136] Next, as shown in FIGS. 18A and 18B, the top yolk-cum-top pole(called top pole in the followings) 27 c of about 3 to 5 μm in thicknessis formed by electroplating through the same procedure as that offorming the top pole tip 27 a and the magnetic path forming pattern 27b. The top pole 27 c takes a shape shown in FIG. 20, for example, beingin a contact and magnetically connected to both the magnetic pathforming pattern 27 b and the top pole tip 27 a. For example, materialswith high saturation flux density such as permalloy (NiFe) or ferrousnitride (FeN) are used as the top pole 17. Here, the top pole 27 ccorresponds to a ‘third magnetic layer portion’ of the invention.

[0137] Next, an overcoat layer 31 made of, for example, alumina isformed covering the whole surface. Then, the thin-film magnetic head iscompleted by forming the air bearing surface (track surface) of therecording head and the reproducing head by performing a slider machiningprocess.

[0138] Only one layer of the thin-film coil 29 is formed here, however,as shown in FIGS. 19A and 19B, a second layer of thin-film coil 35 maybe formed on the insulating layer 30 covering the thin-film coil 29 and,after covering it by the photoresist layer 36, a top pole 37 may beselectively formed thereon.

[0139]FIG. 20 illustrates a plan structure of the top pole 27 c and thetop pole tip 27 a and FIG. 21 illustrates a plan structure of the toppole tip 27 a. As shown in FIG. 20, the top pole 27 c comprises a yolkarea 27 c(1) which occupies most portion of the top pole 27 c having awidth W3 and a connecting area 27 c(2) which overlaps the top pole tip27 a in some portion. The shape of the yolk area 27 c(1) is identical tothe yolk area 17 a of the top pole 17 in the first embodiment. The widthof the connecting area 27 c(2) is made wider than the width of themiddle area 17 b of top pole 17 in the first embodiment. The centers ofeach width direction of the yolk area 27 c(1) and the connecting area 27c(2) are formed to be met mutually.

[0140] As shown in FIG. 21, the top pole tip 27 a has a top area 27 a(1)defining the writing track width on the recording medium and a middlearea 27 a(2) connected to the connecting area 27 c(2) of the top pole 27c. The middle area 27 a(2) has a width W1 which is same as that of themiddle area 17 b of the top pole 17 in the first embodiment, and has alength L4. The top area 27 a(1) has a width W2 which is same as that ofthe top pole 17 c in the first embodiment. The coupling point of the toparea 27 a(1) and the middle area 27 a(2) is almost met with TH0 positionand, at the same time, met with the edge face in front (air bearingside) of the connecting area 27 c(2) of the top pole 27 c. At thecoupling point (that is, TH0 position), the width of the middle area 27a(2) is W1, and that of the top pole 27 a(1) is W2 which is narrowerthan W1. That is, at TH0 position or its vicinity, there is a step inthe width direction between the middle area 27 a(2) and the top area 27a(1). The step face 21 of the middle area 27 a(2) at the step makes anangle τ1 with the side face of the middle area 27 a(2) and makes anangle δ with the side face of the top area 27 a(1). In the embodiment,both angles τ1 and δare almost 90 degrees. That is, both the middle area27 a(2) and the top area 27 a(1) takes a shape of rectangle and the stepface 21 is substantially orthogonal to the side face of the top area 27a(1). Here, the top area 27 a(1) corresponds to a ‘first magnetic layerportion’ of the invention, and the middle area 27 a(2) corresponds to a‘second magnetic layer portion’ of the invention.

[0141] As evident in FIGS. 18 to 20, the top area 27 a(1) is extendingon the flat write gap layer 9, and the middle area 27 a(2) is located onthe insulating pattern 25.

[0142] The values as follows, for example, are preferable as the size ofeach part shown in FIG. 20.

[0143] Width W1 of the middle area 27 a(2)=2.0 to 5.0 μm

[0144] Length L4 of the middle area 27 a(2)=1.0 to 5.0 μm

[0145] Width W2 of the top area 27 a(1)=0.4 to 1.2 μm

[0146] Width W3 of the yolk area 17 a=30 to 40 μm

[0147] Length of the connecting area 27 c (2)=3.0 to 5.0 μm

[0148] The thin-film magnetic head with the top pole having a shapedescribed above exhibits a high performance in overwrite characteristicfor the same reasons as the first embodiment. Further, the magnetic headwith the top pole 27 c and the top pole tip 27 a having shapes asdescribed above has same advantages as the first embodiment in themanufacturing process.

[0149] That is, according to the thin-film magnetic head of theembodiment, widening of the pattern width of the photoresist for formingthe top area 27 a(1) of the top pole tip 27 a can be prevented. As aresult, the writing track width assume smaller and, at the same time, asufficient overwrite character can be maintained by suppressing themagnetic flux occurred in the yolk area 27 c(1) to be saturated beforereaching the top area 27 a(1) of the top pole tip 27 a.

[0150] Further, in the embodiment, forming the photoresist pattern byphotolithography can be performed with high precision since the top pole27 c can be formed on a surface which has been flattened by CMP.

[0151] Further, in the embodiment, a thick insulating film 28 made ofsuch as alumina is formed between the write gap layer 9 and thethin-film coil 10 so that an dielectric withstand voltage between thethin-film coil 10 and the bottom electrode 7 can be increased and, atthe same time, leakage of the magnetic flux from the thin-film coil 10can be decreased.

[0152] The top pole 27 c and the top pole tip 27 a are not limited tothe shapes shown in FIGS. 20 and 21 but may take the shapes shown inFIGS. 22 to 24, for example.

[0153]FIG. 22 is a plan view of the top pole tip 27 a of which bothouter corners of the step face 21 of the middle area 27 a(2) are roundedoff. The structure except for the area which is rounded off is identicalto that of FIG. 21. The rounded angle η of the step face 21 is preferredto be 30 to 60 degrees, for example.

[0154]FIG. 23 illustrates a plan structure in which the connecting area27 c(2) of the top pole 27 c and the middle area 27 a(2) of the top poletip 27 a have tapered shape, and FIG. 24 illustrates a plan structure ofthe top pole tip 27 a. In these figures, the taper angle τ of theconnecting area 27 c(2) of the top pole 27 c is set in a range of, forexample, 45 to 60 degrees, against the edge face 22 of the connectingarea 27 c(2), the taper angle τ1 of the middle area 27 a(2) of the toppole tip 27 a is preferred to be set in a range of, for example, 60 to80 degrees, against the step face 21.

[0155] With the thin-film magnetic head having the top pole 27 c and thetop pole tip 27 a shown in FIGS. 22 to 24, the same effect as thethin-film magnetic head having the top pole 27 c and the top pole tip 27a shown in FIG. 20 can be obtained.

[0156] The position of the edge face 22 in front (air bearing side) ofthe connecting area 27 c(2) of the top pole 27 c does not necessarily bemet exactly with the step face 21 of the top pole tip 27 a which is metwith TH0 position. For example, as shown in FIG. 25, the position of theedge face 22 of the connecting area 27 c(2) may be shifted to the back(opposite of the air bearing surface) of the position of the step face21.

[0157] Further, the connecting area 27 c(2) of the top pole 27 c in thesecond embodiment (FIG. 20) is not essential. For example, as shown inFIG. 26, the top pole 27 c may be composed only of the yolk area 27c(1), and some portion of the yolk area 27 c(1) may be overlapped on themiddle area 27 a(2) of the top pole tip 27 a. In such a case, theposition of the edge face 22 in front (air bearing side) of the yolkarea 27 c(1) does not necessarily be met exactly with the position ofthe step face 21 of the top pole tip 27 a which is met with TH0position. For example, as shown in FIG. 27, the position of the edgeface 22 in front of the yolk area 27 c(1) may be shifted to the back(opposite of the air bearing surface) of the position of the step face21 of the top pole tip 27 a.

[0158] [Third Embodiment]

[0159] A third embodiment of the invention will be described in thefollowings.

[0160]FIG. 28 illustrates a plan structure of the top pole 27 c and thetop pole tip 27 a in the third embodiment of the invention and FIG. 29shows the main part of FIG. 28 being enlarged. In these figures, likenumerals are adopted to the elements which are identical to those shownin FIG. 20 in the second embodiment, and description will be omittedwhen not necessary.

[0161] As shown in FIGS. 28 and 29, in the embodiment, the connectingarea 27 c(2) of the top pole 27 c is extending to overlap a portion ofthe top area 27 a(1) in such a manner that the edge face 22 thereof goesover the position of the step face 21 of the top pole tip 27 a. The edgeface 22 of the connecting area 27 c(2) in the overlapping area isorthogonal to the extending direction of the top area 27 a(1), that is,to the direction of the side face 23 of the top area 27 a(1). Further,in the embodiment, TH0 position is met with the position of the edgeface 22 of the connecting area 27 c(2) but not the position of the stepface 21 of the top pole tip 27 a. Other structures and the manufacturingmethod are identical to those of the second embodiment. For example, thecross sectional structure taken along the face orthogonal to the airbearing surface 20 going through the top area 27 a(1) is identical withthe one shown in FIGS. 18 or 19.

[0162] As described with reference to FIG. 18, the photolithographyprocedure for forming the top pole tip 27 a and the photolithographyprocedure for forming the top pole 27 c are performed separately. As aresult, even if the corner of the photoresist is rounded due to a poorcondition of exposure during the photolithography procedure for formingthe top pole tip 27 a so that the crossing part 24 formed by the stepface 21 of the top pole tip 27 a and the side face 23 of the top area 27a(1) does not assume a corner with a sharp right angle, that is, thecrossing part 24 is rounded off, as shown in FIG. 29, the side face 23of the top area 27 a(1) and the connecting area 27 c(2) of the top pole27 c invariably makes a sharp right angle. That is, the width of the toparea 27 a(1) for defining the track width of the recording medium ismade to be W1 precisely through the whole region from TH0 position tothe air bearing surface (i.e. whole region of throat height TH).Accordingly, in a case where the width W1 of the top area 27 a(1) ismade less than 1 μm or, further, less than 0.5 μm in accordance withnarrowing of the track width, the width W1 of the top area 27 a(1) isnot widened at TH0 position or in the vicinity of TH0 position.Especially, even in a case where the value of the throat height TH isreduced from the value of about 1 μm to the value of 0.5 to 0.2 μm toobtain the thin-film magnetic head with higher performance, a precisedesign value width W1 can be guaranteed all through the region of thethroat height TH. As a result, the recording track width on therecording medium can be controlled precisely, and a sidewrite phenomenonin which a data to be written on a specific track is written on aneighboring track can be effectively prevented.

[0163] Further, in the embodiment, the connecting area 27 c(2) whichspreads in the width direction of the top area 27 a(1) is being placedimmediately behind TH0 position of the top area 27 a(1) and, at the sametime, the middle area 27 a(2) is being placed immediately behind thestep face 21, so that a sufficient magnetic volume is maintained. As aresult, saturation of the magnetic flux occurred in the yolk area 27c(1) before reaching the top area 27 a(1) of the top pole tip 27 a canbe effectively prevented, and a sufficient overwrite characteristic canbe maintained.

[0164] In a case where the edge face 22 of the connecting area 27 c(2)of the top pole 27 c is placed in a position over the step face 21 ofthe top pole tip 27 a like the embodiment, the shape of the top pole tip27 a and the top pole 27 c are not limited to the ones shown in FIG. 28.As shown in FIG. 30, for example, the connecting area 27 c(2) of the toppole 27 c and the middle area 27 a(2) of the top pole tip 27 a may takethe shapes with taper, respectively. The taper angle of the connectingarea 27 c(2) of the top pole 27 c and the taper angle of the middle area27 a(2) of the top pole tip 27 a are preferred to be made same as in thecase of FIG. 23.

[0165] Further, as shown in FIG. 31, the top pole 27 c can be composedonly of the yolk area 27 c(1) without the connecting area 27 c(2) andthe yolk area 27 c(1) may be overlapped so that the end frame face 22 ofthe yolk area 27 c(1) is placed on the top area 27 a(1) going over thestep face 21 of the top pole tip 27 a.

[0166] Further, as shown in FIG. 32, the step face 21 of the top poletip 27 a and the side face 23 of the top area 27 a(1) may make an anglelarger than 90 degrees. However, it is preferable to make the angle 90degrees between the step face 21 and the side face 23.

[0167] In the second and third embodiment, a case in which the top polearea of the thin-film magnetic head is formed being divided into twoparts such as the top pole 27 c and the top pole tip 27 a and, at thesame time, the whole thin-film magnetic head has a cross sectionalstructure as shown in FIG. 19, however, the invention is not limited tothe embodiment. The structures in a fourth and fifth embodimentsdescribed in the followings may also be applicable.

[0168] [Fourth Embodiment]

[0169] Next, a method of manufacturing a composite thin-film magnetichead as a method of manufacturing the thin-film magnetic head of thefourth embodiment of the invention will be described with reference toFIG. 33A and FIG. 33B to FIG. 35A and FIG. 35B. The thin-film magnetichead of the invention is specified in the method of manufacturing of thethin-film magnetic head of the embodiment so that both together bedescribed in the followings. Each of FIG. 33A to FIG. 35A shows a crosssectional view orthogonal to the air bearing surface and each of FIG.33B to FIG. 35B shows a cross sectional view parallel to the air bearingsurface of the pole area. In these figures, like numerals are adopted tothe elements which are identical to those of the forgoing embodimentsrespectively.

[0170] In the method of manufacturing the thin-film magnetic head, adescription of the procedure until forming the bottom pole 7 shown inFIG. 33A and FIG. 33B is omitted since it is identical to the procedureshown in FIG. 1A and FIG. 1B to part of FIG. 3A and FIG. 3B of the firstembodiment.

[0171] In the embodiment, after forming the bottom electrode 7, a bottompole tip 41 a and a bottom connecting area 41 b of about 2.0 to 2.5 μmin thickness are formed on the bottom electrode 7 as shown in FIG. 33Aand FIG. 33B. Here, the bottom pole tip 41 a is formed to be extendedfrom the area near the air bearing surface (i.e. the vicinity of an MR(GMR) height 0 position) to the throat height 0 position. The bottompole tip 41 a and the bottom connecting area 41 b may be formed as aplated film such as NiFe, or as a sputtered film such as FeN, FeZrNP, orCoFeN.

[0172] Next, an insulating film 42 of 0.3 to 0.6 μm in thickness made ofan insulating material such as alumina is formed all over the surfaceby, for example, sputtering method or CVD method.

[0173] Next, a first thin-film coil 43 of 1.5 to 2.5 μm in thicknessmade of such as copper (Cu) for an inductive recording head is formed ina concave region formed between the bottom pole tip 41 a and the bottomconnecting area 41 b by, for example, electroplating. Here, at the sametime, a coil connecting area 43C for connecting the thin-film coil 43and a second layer of thin-film coil which will be described in thefollowing is formed in a back region (right-hand side region in thefigure) of the bottom connecting area 41 b.

[0174] Next, an insulating film 44 of 3.0 to 4.0 μm in thickness made ofan insulating material such as alumina is formed all over the surface bysputtering method, then, the surface thereof is flatten by, for example,CMP method to have the top surface of the bottom pole tip 41 a and thebottom connecting area 41 b exposed.

[0175] Next, as shown in FIG. 34A and FIG. 34B, a write gap layer 9 of0.2 to 0.3 μm in thickness made of, for example, an alumina insulatingmaterial is formed by sputtering method. The write gap layer 9 may beformed with materials such as aluminum nitride (AlN), silicon oxide, andsilicon nitride other than alumina. An opening 9 a for connecting thetop pole and the bottom pole is formed by patterning the write gap layer9 through photolithography and, at the same time, an opening 9 b toexposure the coil connecting area 43C is formed by patterning the writegap layer 9 and the insulating layer 44.

[0176] Further, a top pole tip 45 a is formed on the write gap layer 9,and a top connecting area 45 b for magnetically coupling the top poleand the bottom pole is formed so as to overlap with the bottomconnecting area 41 b and to have a contact therewith. On the other hand,the top pole tip 45 a is formed extending longer than the bottom poletip 41 a in a backward direction from the air bearing surface. The toppole tip 45 a is formed, like the third embodiment (shown in such asFIG. 28), having the middle area 27 a(2) for maintaining a magneticvolume, the top area 27 a(1) for defining the track width and the stepface 21 at the coupling point. The plan shape of top pole tip 45 a issame as that shown in FIGS. 28, 30, 31, or 32. Further, the top pole tip45 a is to be placed so that the step face 21 is located in a positionslightly backward of the edge face position (that is, TH0 position)which is in the back side of the bottom pole tip 41 a.

[0177] Further, the write gap layer 9 and the bottom pole tip 41 a areetched in a self-aligned manner using the top pole tip 45 a as a mask.That is, after selectively removing the write gap layer 9 through RIE bychlorine system gas (Cl₂, CF₄, BCl₂, SF₆, and so on), using the top poletip 45 a as a mask, a trim structure is formed by further etching theexposed bottom pole tip 41 a about 0.3 to 0.6 m by, for example, ionmilling with Ar.

[0178] Further, an insulating layer 46 of 0.3 to 0.6 in thickness madeof such as alumina is formed all over the surface by, for example,sputtering method or CVD method. Next, a second layer of thin-film coil47 of 1.5 to 2.5 μm in thickness made of copper (Cu) for an inductiverecording head is formed by, for example, electroplating on theinsulating film 46 in the concave area formed between the top pole tip45 a and the top connecting area 45 b. Here, at the same time, the coilconnecting area 47C which has a contact with the coil connecting area43C through the opening area 9 b is formed.

[0179] Further, an insulating layer 48 of about 3 to 4 μm in thicknessmade of such as alumina is formed all over the surface by, for example,sputtering method or CVD method. The insulating layer 48 and theinsulating film 46 may be formed with insulating materials, other thanalumina, such as silicon dioxide (SiO₂) and silicon nitride (SiN).

[0180] Next, polishing is performed by, for example, CMP method so thatthe top surface of the top pole tip 45 a and the top connecting area 45b is exposed. As a result, the surface of the top pole tip 45 a and thetop connecting area 45 b is flattened so as to have a same surface levelas that of the insulating layer 48 and the insulating firm 46.

[0181] Next, as shown in FIG. 35A and FIG. 35B, a top pole 49 of about 3to 4 μm in thickness made of, for example, the same material with thetop pole tip 45 a is selectively formed by, for example, electroplatingor sputtering method. Here, some portion of the top pole 49 overlapswith the top pole tip 45 a and a position of the edge face 22 which isin the front side (air bearing surface side) of the top pole 49 isplaced to meet the position of the back-side edge (that is, TH0position) of the bottom pole tip 41 a. Further, the backside edgeposition of the top pole 49 is placed being in touch with the topconnecting area 45 b. As a result, the top pole 49 is magneticallyconnected to the top pole tip 45 a and, at the same time, magneticallyconnected to the bottom pole 7 through the top connecting area 45 b andthe bottom connecting area 41 b.

[0182] Further, an overcoat layer 50 of about 30 μm in thickness made ofsuch as alumina is formed all over the surface by, for example,sputtering. Then, the thin-film magnetic head is completed by formingthe air bearing surface (ABS) of the recording head and the reproducinghead through applying slider machining process.

[0183] In the embodiment, the top pole 49 is formed with the position ofthe front-side edge face 22 being at TH0 position and, at the same time,being in forward position of the step face 21 of the top pole tip 45 a.As a result, such an effect as that of the third embodiment as shown inFIG. 29 can be obtained.

[0184] [Fifth Embodiment]

[0185] A method of manufacturing a composite thin-film magnetic head asthe method of manufacturing the thin-film magnetic head according to afifth embodiment of the invention will be described with reference toFIG. 36A to FIG. 38B. The thin-film magnetic head of the invention isspecified in the method of manufacturing the thin-film magnetic head ofthe embodiment so that both together be described in the followings.Each of FIG. 36A to FIG. 38A shows a cross sectional view orthogonal tothe air bearing surface and each of FIG. 36B to FIG. 38B shows a crosssectional view parallel to the air bearing surface of the pole area. Inthese figures, like numerals are adopted to the elements which areidentical to those of the forgoing embodiments respectively.

[0186] In the method of manufacturing the thin-film magnetic head, adescription of the procedure until forming the bottom pole 7 as shown inFIG. 36A and FIG. 36B is omitted since it is identical to the procedureshown in FIG. 1A and FIG. 1B to part of FIG. 3A and FIG. 3B of the firstembodiment.

[0187] In the embodiment, after forming the bottom electrode 7, a bottompole tip 61 a and a bottom connecting area 61 b are formed on the bottomelectrode 7 as shown in FIG. 36A and FIG. 36B. Here, the bottom pole tip41 a is formed to be extended from the area near the air bearing surface(i.e. the vicinity of an MR (GMR) height 0 position) to the throatheight 0 position.

[0188] Next, an insulating film 62 of 3.0 to 4.0 μm in thickness made ofan insulating material such as alumina is formed all over the surface bysputtering method, then, flatten all of the surface by, for example, CMPmethod to have the top surface of the bottom pole tip 61 a and thebottom connecting area 61 b exposed.

[0189] Next, as shown in FIG. 37A and FIG. 37B, the write gap layer 9 of0.2 to 0.3 μL m in thickness made of, for example, an alumina insulatingmaterial is formed by sputtering method. The opening 9 a for connectingthe top pole and the bottom pole is formed by patterning the write gaplayer 9 through photolithography.

[0190] Next, a top pole tip 63 a is formed on the write gap layer 9, anda top connecting area 63 b for magnetically coupling the top pole andthe bottom pole is formed so as to overlap with the bottom connectingarea 61 b and to have a contact therewith. On the other hand, the toppole tip 63 a is formed extending longer than the bottom pole tip 61 ain a backward direction from the air bearing surface. The top pole tip63 a is formed, like the third embodiment (shown in such as FIG. 28),having the middle area 27 a(2) for maintaining a magnetic volume, thetop area 27 a(1) for defining the track width and the step face 21 atthe coupling point. The plan shape of top pole tip 63 a is same as thatshown in FIGS. 28, 30, 31, or 32. Further, the top pole tip 63 a is tobe placed so that the step face 21 is located in a position slightlybackward of the edge face position (that is, TH0 position) which is inthe back side of the bottom pole tip 61 a.

[0191] Further, a trim structure is formed by etching the write gaplayer 9 and the bottom pole tip 61 a in a self-aligned manner using thetop pole tip 63 a as a mask.

[0192] Next, a first layer of thin-film coil 64 of 1.5 to 2.5 μm inthickness made of copper (Cu) for an inductive recording head is formedby, for example, electroplating on the write gap layer 9 in the concavearea formed between the top pole tip 63 a and the top connecting area 63b. Here, at the same time, the coil connecting area 64C for coupling thethin-film coil 64 and a second layer of thin-film coil which will bedescribed in the following is formed in a back region (right-hand sideregion in the figure) of the top connecting area 63 b.

[0193] Next, as shown in FIG. 38A and FIG. 38B, an insulating film 65 of3.0 to 4.0 μm in thickness made of an insulating material such asalumina is formed all over the surface by sputtering method, then, thesurface thereof is flattened by, for example, CMP method to have the topsurface of the bottom pole tip 63 a and the bottom connecting area 63 bexposed.

[0194] Next, an opening 65 a reaching the coil connecting area 64C isformed by selectively etching the insulating layer 65.

[0195] Next, a second layer of a thin-film coil 66 of 1.5 to 2.5 μm inthickness made of such as copper (Cu) for an inductive recording head isformed on the insulating layer 65 by, for example, electroplating. Here,at the same time, a coil connecting area 66C having a contact with theconnecting area 64C through the opening 65 a is formed.

[0196] Next, a photoresist layer 67 covering the thin-film coil 66 andthe coil connecting area 64C is formed by photolithography with highprecision, then, a heat treatment at 250° C. is applied to have thesurface of the photoresist layer 67 flattened and turn of the thin-filmcoil 66 insulated to each other.

[0197] Next, a top pole 68 of about 3 to 4 μm in thickness made of, forexample, the same material with the top pole tip 63 a is selectivelyformed by, for example, electroplating or sputtering method. Here, aportion of the top pole 68 overlaps with the top pole tip 63 a and aposition of the edge face 22 which is in the front side (air bearingsurface side) of the top pole 68 is placed to meet the position of theback-side edge (that is, TH0 position) of the bottom pole tip 61 a.Further, the back-side edge position of the top pole 68 is placed beingin touch with the top connecting area 63 b. As a result, the top pole 68is magnetically coupled to the top pole tip 63 a and, at the same time,magnetically coupled to the bottom pole 7 through the top connectingarea 63 b and the bottom connecting area 61 b.

[0198] Further, an overcoat layer 69 of about 30 μm in thickness made ofsuch as alumina is formed all over the surface by, for example,sputtering. Then, the thin-film magnetic head is completed by formingthe air bearing surface (ABS) of the recording head and the reproducinghead through applying a slider machining process.

[0199] With the embodiment, same operation and effect as the third andfourth embodiments can be obtained. That is, a sidewrite phenomenon canbe effectively prevented by precisely controlling the recording trackwidth on the recording medium and, at the same time, a sufficientoverwrite characteristic can be maintained.

[0200] Further, in the embodiment, the top pole tip 63 a can be formedon a flattened area so that a photoresist pattern can be formed byphotolithography with high precision. As a result, a width of the toparea 27 a(1) of the top pole tip 63 a can be micronized as precise as0.5 to 0.25 μm.

[0201] The invention has been described in the forgoing embodiments,however, it is not limited to the embodiments but may be practiced stillother way with modifications. For example, the method of manufacturingthe composite thin-film magnetic head is described in the forgoingembodiments and the modification examples, however, the invention may beapplied to a thin-film magnetic head for recording only or a thin-filmmagnetic head for recording and reproducing, having an inductionmagnetic transducer for writing. The invention may be applied to athin-film magnetic head in which an element for writing and an elementfor reading are stacked in a reverse order.

[0202] As described above, according to the thin-film magnetic head andthe method of manufacturing the same of the invention, at least one ofthe two magnetic layers include a first magnetic layer portion with aconstant width for defining a width of a recording track of a recordingmedium extending from a recording medium opposite surface facing to therecording medium to an edge of the insulating layer closer to therecording medium or its vicinity; and a second magnetic layer portionmagnetically coupled to the first magnetic layer portion at the edge ofthe insulating layer or its vicinity. A step in the width direction isformed in a coupling point of the first magnetic layer portion and thesecond magnetic layer portion so as to have a width of the firstmagnetic layer portion at the coupling point smaller than a width of thesecond magnetic layer portion at the coupling point. Accordingly, aninfluence of an unnecessary reflection from the undercoat layer in thephotolithography procedure of forming the first magnetic layer portioncan be suppressed so as to have the width of the first magnetic layerformed precisely and, at the same time, a magnetic flux occurred throughthin-film coils is prevented from being saturated in the second magneticlayer portion before reaching the first magnetic layer portion. As aresult, the width of the first magnetic layer portion can be micronizedto, for example, sub-microns and, at the same time, an effect ofmaintaining an sufficient overwrite characteristic can be obtained.

[0203] According to other thin-film magnetic head and the method ofmanufacturing the same, a step face of the second magnetic layer portionat the coupling point is substantially orthgonal to the extendingdirection of the first magnetic layer portion. Accordingly, an influenceof an unnecessary reflection from the undercoat layer in thephotolithography procedure for forming the first magnetic layer portionis effectively suppressed, and the width of the first magnetic layerportion is more precisely formed.

[0204] Further, according to still another thin-film magnetic head orthe method of manufacturing the same, the third magnetic layer portionis placed overlapping a portion of the first magnetic layer portiongoing over the coupling point; and an edge face of the third magneticlayer portion closer to a recording medium in the overlapping area isorthogonal to the extending direction of the first magnetic layerportion. As a result, the width of the first magnetic layer portionwhich determines the recording track width of the recording mediumbecomes exactly constant without being influenced all through the areafrom the orthogonally crossing point to the top area, even if a concavecorner of the step of the width direction at the coupling point isrounded off. As a result, the width of the recording track of therecording medium can be precisely controlled.

[0205] Further, according to the thin-film magnetic head or the methodof manufacturing the same of the invention, a position of the edge faceof the third magnetic layer portion is met with a position of the edgeof the insulating layer closer to a recording medium, so that the widthof the first magnetic layer becomes exactly constant all through thewhole range of so-called throat height, and the width of the recordingtrack of the recording medium can be more precisely controlled.

[0206] Further, according to the thin-film magnetic head or the methodof manufacturing the same of the invention, even if a bad influence ofthe condition of exposure in the photolithography procedure for formingthe first magnetic layer occurs due to the fact that the second magneticlayer is formed on the slope, having a comparatively large rounded partin the concave corner of the step in the width direction at the couplingpoint, varying of the substantial width of the first magnetic layerportion can be avoided. That is, stabilizing the width of the pole forrecording formed on the slope, which was difficult hitherto, can beperformed.

[0207] Obviously many modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that within the scope of the appended claimsthe invention may be practiced otherwise than as specifically described.

What is claimed is:
 1. A thin film magnetic head comprising: a first insulating layer as a write gap layer; a second insulating layer provided in a predetermined area on a recording medium side in contact with a surface of the first insulating layer; first and second magnetic layers including two magnetic poles which face each other with the first insulating layer in between and are positioned to face with a recording medium, the first and second magnetic layers being magnetically coupled to each other in a back gap area on an opposite side of an air-bearing surface facing the recording medium, the first magnetic layer having a magnetic pole tip which has a uniform width portion for defining a write track width on the recording medium and extends from the air-bearing surface to a predetermined position on the second insulating layer in contact with the surfaces of the first and second insulating layers, a magnetic pole coupler located in the back gap area in contact with the second magnetic layer, and a yoke which magnetically couples the magnetic pole tip with the magnetic pole coupler; a thin film coil located between the first and second magnetic layers; a third insulating layer covering an inner surface of a recessed space surrounded by the first and second insulating layers, the magnetic pole tip, and the magnetic pole coupler, wherein a recording-medium-side edge of the second insulating layer defines a reference position to the air-bearing surface; and a surface of the magnetic pole tip, the surface being on a side opposite to the first insulating layer, and edge surfaces of the third insulating layer, are planarized in one plane.
 2. A method of manufacturing a thin film magnetic head comprising steps of: forming a first insulating layer as a write gap layer; providing a second insulating layer in a predetermined area on a recording medium side in contact with a surface of the first insulating layer; forming first and second magnetic layers to be magnetically coupled to each other in a back gap area on an opposite side of an air-bearing surface facing the recording medium, the first and second magnetic layers including two magnetic poles which face each other with the first insulating layer in between and are positioned to face with a recording medium, the first magnetic layer having a magnetic pole tip which has a uniform width portion for defining a write track width on the recording medium and extends from the air-bearing surface to a predetermined position on the second insulating layer in contact with the surfaces of the first and second insulating layers, a magnetic pole coupler located in the back gap area in contact with the second magnetic layer, and a yoke which magnetically couples the magnetic pole tip with the magnetic pole coupler; forming a thin film coil between the first and second magnetic layers; forming a third insulating layer to cover an inner surface of a recessed space surrounded by the first and second insulating layers, the magnetic pole tip, and the magnetic pole coupler; and planarizing a surface of the magnetic pole tip to form one plane with at least edge surfaces of the third insulating layer, the surface of the magnetic pole tip being on a side opposite to the first insulating layer, wherein the second insulating layer is formed so that a recording-medium-side edge of the second insulating layer defines a reference position to the air-bearing surface in the step of forming the second insulating layer.
 3. A thin film magnetic head comprising: a write gap layer made of non-magnetic material; a reference layer made of non-magnetic material selectively provided in a predetermined area on a recording medium side in contact with a surface of the write gap layer; first and second magnetic layers including two magnetic poles which face each other with the write gap layer in between and are positioned to face with a recording medium, the first and second magnetic layers being magnetically coupled to each other in a back gap area on an opposite side of an air-bearing surface facing the recording medium, the first magnetic layer having a magnetic pole tip which has a uniform width portion for defining a write track width on the recording medium and extends from the air-bearing surface to a predetermined position on the reference layer in direct contact with the surfaces of the write gap layer and the reference layer, a magnetic pole coupler located in the back gap area in contact with the second magnetic layer, and a yoke which magnetically couples the magnetic pole tip with the magnetic pole coupler; a thin film coil located between the first and second magnetic layers; an insulating layer covering an inner surface of a recessed space surrounded by the write gap layer, the reference layer, the magnetic pole tip, and the magnetic pole coupler, wherein a recording-medium-side edge of the reference layer defines a reference position to the air-bearing surface; and a surface of the magnetic pole tip, the surface being on a side opposite to the write gap layer, and edge surfaces of the insulating layer are planarized in one plane.
 4. A method of manufacturing a thin film magnetic head comprising steps of: forming a write gap layer made of non-magnetic material; selectively providing a reference layer made of non-magnetic material in a predetermined area on a recording medium side in contact with a surface of the write gap layer; forming first and second magnetic layers to be magnetically coupled to each other in a back gap area on an opposite side of an air-bearing surface facing the recording medium, the first and second magnetic layers including two magnetic poles which face each other with the write gap layer in between and are positioned to face with a recording medium, the first magnetic layer having a magnetic pole tip which has a uniform width portion for defining a write track width on the recording medium and extends from the air-bearing surface to a predetermined position on the reference layer in direct contact with the surfaces of the write gap layer and the reference layer, a magnetic pole coupler located in the back gap area in contact with the second magnetic layer, and a yoke which magnetically couples the magnetic pole tip with the magnetic pole coupler; forming a thin film coil between the first and second magnetic layers; forming an insulating layer to cover an inner surface of a recessed space surrounded by the write gap layer, the reference layer, the magnetic pole tip, and the magnetic pole coupler; and planarizing a surface of the magnetic pole tip to form one plane with at least edge surfaces of the insulating layer, the surface of the magnetic pole tip being on a side opposite to the write gap layer, wherein the reference layer is formed so that a recording-medium-side edge of the reference layer defines a reference position to the air-bearing surface in the step of forming the reference layer. 